$7fg - 8fh + 10f + 10 = -10g + 4$ Solve for $f$.
Explanation: Combine constant terms on the right. $7fg - 8fh + 10f + {10} = -10g + {4}$ $7fg - 8fh + 10f = -10g - {6}$ Notice that all the terms on the left-hand side of the equation have $f$ in them. $7{f}g - 8{f}h + 10{f} = -10g - 6$ Factor out the $f$ ${f} \cdot \left( 7g - 8h + 10 \right) = -10g - 6$ Isolate the $f$ $f \cdot \left( {7g - 8h + 10} \right) = -10g - 6$ $f = \dfrac{ -10g - 6 }{ {7g - 8h + 10} }$ We can simplify this by multiplying the top and bottom by $-1$. $f= \dfrac{10g + 6}{-7g + 8h - 10}$